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CVE Record

CVE-2021-47392: RDMA/cma: Fix listener leak in rdma_cma_listen_on_all() failure

In the Linux kernel, the following vulnerability has been resolved: RDMA/cma: Fix listener leak in rdma_cma_listen_on_all() failure If cma_listen_on_all() fails it leaves the per-device ID still on the listen_list but the state is not set to RDMA_CM_ADDR_BOUND. When the cmid is eventually destroyed cma_cancel_listens() is not called due to the wrong state, however the per-device IDs are still holding the refcount preventing the ID from being destroyed, thus deadlocking: task:rping state:D stack: 0 pid:19605 ppid: 47036 flags:0x00000084 Call Trace: __schedule+0x29a/0x780 ? free_unref_page_commit+0x9b/0x110 schedule+0x3c/0xa0 schedule_timeout+0x215/0x2b0 ? __flush_work+0x19e/0x1e0 wait_for_completion+0x8d/0xf0 _destroy_id+0x144/0x210 [rdma_cm] ucma_close_id+0x2b/0x40 [rdma_ucm] __destroy_id+0x93/0x2c0 [rdma_ucm] ? __xa_erase+0x4a/0xa0 ucma_destroy_id+0x9a/0x120 [rdma_ucm] ucma_write+0xb8/0x130 [rdma_ucm] vfs_write+0xb4/0x250 ksys_write+0xb5/0xd0 ? syscall_trace_enter.isra.19+0x123/0x190 do_syscall_64+0x33/0x40 entry_SYSCALL_64_after_hwframe+0x44/0xa9 Ensure that cma_listen_on_all() atomically unwinds its action under the lock during error.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

This Linux kernel issue can leave RDMA connection-management listener objects stuck after an internal listen setup failure. Cleanup then waits forever because references are never released, causing a deadlock. Business impact is most relevant on systems using RDMA-capable networking or RDMA kernel modules, where affected kernels could suffer a local availability failure.

Executive priority

Treat this as a targeted availability risk, not a broad internet-facing emergency based on the provided evidence. Patch through normal kernel maintenance, with higher priority for RDMA-dependent production systems where deadlocks could disrupt compute, storage, or low-latency services.

Technical view

The RDMA CMA listen-on-all error path left per-device IDs on listen_list without setting RDMA_CM_ADDR_BOUND. Later destruction skipped cma_cancel_listens because state was wrong, while child IDs still held references. The kernel fix atomically unwinds the failed listen setup under the lock.

Likely exposure

Exposure appears limited to Linux hosts running affected kernel versions with RDMA CMA functionality available or in use. The source bundle lists affected Linux kernel versions including 5.11, 5.10.71, 5.14.10, and 5.15, but does not provide distribution package mappings.

Exploitation context

The bundle does not report active exploitation, and KEV is false. The described failure mode is a deadlock during RDMA user connection-management cleanup after a listen-on-all failure. No remote exploitability, privilege requirement, or public weaponization evidence is provided.

Researcher notes

Evidence is confined to the Linux kernel fix description and stable commit references. There is no CVSS score, CWE, KEV listing, exploit report, or distribution-specific fixed package data in the bundle. Avoid extrapolating beyond RDMA CMA deadlock and cleanup behavior.

Mitigation direction

  • Update to a vendor kernel containing the referenced stable RDMA CMA fixes.
  • Check Linux distribution advisories for package-specific fixed versions.
  • Prioritize RDMA-enabled servers, HPC clusters, storage fabrics, and low-latency networking hosts.
  • If patching is delayed, consult vendor guidance for RDMA-specific risk reduction.

Validation and detection

  • Inventory Linux kernel versions on systems with RDMA hardware or RDMA modules.
  • Check whether vendor kernel changelogs include CVE-2021-47392 or the referenced commits.
  • Confirm RDMA CMA services or workloads are present before assigning operational priority.
  • Monitor affected hosts for stuck uninterruptible tasks involving rdma_cm or rdma_ucm.
Prepared
Confidence
medium
Sources
5

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

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CVE-2021-47392 mapping review

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Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

0CVSS vectors
3Timeline events
2ADP providers
4Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: noneAutomatable: noTechnical Impact: partial

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. CVE publishedCVE Program

    The CVE record was published.

  3. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

ADP provider summaries

CVECVE Program Container
CISA-ADPCISA ADP Vulnrichment
other:ssvc

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinux70ba8b1697e35c04ea5f22edb6e401aeb1208d96, c80a0c52d85c49a910d0dc0e342e8d8898677dc0, c80a0c52d85c49a910d0dc0e342e8d8898677dc0unaffected
LinuxLinux5.11, 0, 5.10.71, 5.14.10, 5.15affected
Weakness

CWE details

No CWE listed

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